The answer to this is D. People believed that if in case a person returns from the dead, this is not always a good thing. There is a possibility that the person will only be a fraction of how he used to be when he was alive.
This means that if his son would return back from the dead, it might be for the intention of harming him and his wife and this is not something that he would like to experience or think about.
There are some things that people wish for without realizing the complications that may occur because of it. Some wishes may seem perfect but when done in a hurry, they may not give the results that people would want to get.